Research in primary care settings is expanding, because it allows evaluation of common and chronic conditions across the full spectrum of severity in large populations of patients. Nevertheless, the representativeness and generalizability of practice-based findings remain in question. It is necessary to document patient characteristics to determine whether they are representative of pediatric practices an the area population. This project will comprehensively assess the representativeness of patients visiting practices in the Pediatric Practice Research Group (PPRG) by documenting the characteristics of families within each of these pediatric practices. The project will also assess mobility of patients within the PPRG practices, an issue critical in determining the feasibility of developing patient registries for longitudinal practice- based research. Further, it will examine whether indigent/minority families demonstrate more mobility than other PPRG families. Parental self-report of sociodemographic data will be collected during a nine month period with repeat visits to practices to account for seasonal variations. Data analysis will include crosstabulation, analysis of variance, correlation and multivariate analyses. The proposed study will allow the PPRG to address issues of external validity/selection bias/population representativeness when evaluating ongoing and future practice-based research efforts.